Multi-axial orthopedic device and system

ABSTRACT

Embodiments of an orthopedic implant device and system, and methods for implanting them, are disclosed. The implant may include a receiver member having a channel for accommodating an elongated rod or other longitudinal member, a bone anchoring member such as a screw or hook, and a base member rotatable with respect to the receiver member for retaining the bone anchoring member in the receiver member. The base member is configured to allow at least two different degrees of maximum angulation of the bone anchoring member with respect to the receiver member. The number and relative direction of such angulations are independent of the orientation of the channel or other part of the receiving member.

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/496,536, filed Aug. 20, 2003.

FIELD OF THE INVENTION

The disclosed subject matter generally relates to implants used forcorrection of orthopedic injuries or deformities, and more specifically,but not exclusively, concerns apparatuses and methods for fixing aportion of the spine to allow correction or healing thereof.

BACKGROUND

In the realm of neurologic, orthopedic and spinal surgery, it is wellknown to use implants to fix the position of bones. In this way, thehealing of a broken bone can be promoted, and malformations or otherinjuries can be corrected. For example, in the field of spinal surgery,it is well known to place such implants into vertebrae for a number ofreasons, including (a) to correct an abnormal curvature of the spine,including a scoliotic curvature, (b) to maintain appropriate spacing andprovide support to broken or otherwise injured vertebrae, and (c) toperform other therapies on the spinal column.

Typical implant systems include several pieces, which may be associatedor useful with only specific other pieces. Among such pieces are screws,hooks rods, plates and similar longitudinal members for supporting,holding and/or correcting one or more bones. Such longitudinal memberscan be fastened to bones via direct or indirect connection to hooks,screws, bolts or other fasteners, and can be linked to each other by avariety of connectors. In the spinal field, for example, screws or otherfasteners can be attached to two or more vertebrae, the vertebrae can beadjusted into their normal or a therapeutically better position, andlongitudinal members are connected to the fasteners so that thevertebrae are held in the normal or therapeutically improved position.Interbody devices, such as intervertebral cages or spacers to maintainthe space and positioning of two adjacent vertebrae with respect to eachother are also known.

Accordingly, known bone screws, hooks, clamps and other bone fastenersor fixation devices can be connected or adjoined to a particular bone orbones as a connection between the remainder of the implant and thebone(s). Specially formed plates or rods are commonly used asstabilization and support members. Thus, in a common spinal implantsystem, a spinal plate is implanted along one or more vertebrae bydriving a bone screw through the plate and into each of two vertebrae.The vertebrae are thus supported and kept in a particular position bythe plate, so as to promote correction or healing.

Where a rod is used as a support and stabilizing member, commonly aseries of two or more screws are inserted into two or more vertebrae tobe instrumented. A rod is then placed within or coupled to the heads ofthe screws, or is placed within a connecting device that links the rodand a screw head, and the connections are tightened. In this way, arigid supporting structure is fixed to the vertebrae, with the rodproviding the support that maintains and/or promotes correction of thevertebral malformation or injury.

Many varieties of bone fixation devices (e.g. screws and hooks) aremonoaxial in construction. That is, such devices are connected to therod or plate such that a longitudinal axis through the rod or plate anda longitudinal axis through the fixation device are capable of only asingle position with respect to each other. While useful in certaincircumstances, in some therapeutic situations such an inflexible deviceis impractical, or can lead to a longer duration of surgery.

More recently, bone fixation devices having multi-axial capability havebeen introduced. Examples of such constructs are shown in U.S. Pat. Nos.5,797,911, 5,954,725, and 6,280,445. These devices allow one or moredegrees of freedom between a fastening portion or fastening member and areceiving portion or member, reducing the required precision ofplacement of the fixation device, since a head portion of the fixationdevice is multi-axially positionable around the bone-threaded or hookportion. The head can thus be positioned so as to easily receive therod, limiting or removing much of the positioning difficulty inherent inprior devices. However, such devices provide a single maximum anglebetween the fastening portion and the receiving portion for everyrelative orientation of those parts. Other devices have made possible alarger maximum angle between the fastening portion and the receivingportion when the fastening portion occupies one position with respect tothe receiving portion, but allow only a smaller maximum angle when thefastening portion occupies any other position with respect to thefastening portion.

SUMMARY OF THE INVENTION

In one embodiment, the disclosure includes a bone fixation systemincluding a receiver member having a longitudinal axis, a bone anchoringmember having a head portion and a bone-engaging portion, the boneanchoring member having at least a first maximum angular position and asecond maximum angular position relative to the axis, wherein the secondmaximum angular position includes a greater angle relative to the axisthan the first maximum angular position, and a base member rotatablyconnected to the receiver member, the base member having at least onewall defining an opening that allows the bone anchoring member to occupyeither of the first maximum angular position and the second maximumangular position. The system may also include an elongated memberconnected to the receiver member.

In another embodiment, an orthopedic implant apparatus is providedincluding a receiver member having at least one wall defining a channelfor receiving at least a portion of an elongated body, the receivermember having a longitudinal axis, a bone anchoring member having a headportion and a bone-engaging portion, and a base member rotatablyconnected to the receiver member, the base member permitting multi-axialpositioning of the bone attachment member with respect to the receivermember. The base member and the bone anchoring member have a firstrelative position wherein the maximum angle between the bone anchoringmember and the axis is a first value. Other relative positions of thebase member and the bone attachment member allow a maximum angle betweenthe bone anchoring member and the axis that is less than the firstvalue, and the first relative position is independent of the orientationof the channel of the receiver member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an orthopedic implant system accordingto one embodiment of the present invention.

FIG. 2 is a perspective view of a portion of an orthopedic implantsystem similar to the embodiment of FIG. 1.

FIG. 3 is an exploded view of an orthopedic implant according to oneembodiment of the present invention.

FIG. 4 is a side cross-sectional view of the assembled embodiment of theorthopedic implant shown in FIG. 3.

FIG. 5 is a side cross-sectional view of another embodiment of areceiver member useful with the embodiment of the orthopedic implantshown in FIG. 3.

FIG. 6 is a top view of aspects of the embodiment of the orthopedicimplant shown in FIG. 3.

FIG. 7 is a side view of the aspects of the embodiment of the orthopedicimplant shown in FIG. 6A.

FIG. 8 is a perspective view of an embodiment of a base or retainingmember useable with the embodiment of an orthopedic implant shown inFIG. 3.

FIG. 9 is a perspective view of another embodiment of a base orretaining member useable with the embodiment of an orthopedic implantshown in FIG. 3.

FIG. 10 is a side cross-sectional view of an orthopedic implantaccording to another embodiment of the present invention.

FIG. 11 is a side cross-sectional view of an orthopedic implantaccording to yet another embodiment of the present invention.

FIG. 12 is a side cross-sectional view of an orthopedic implantaccording to still another embodiment of the present invention.

FIG. 13 is a side cross-sectional view of an orthopedic implantaccording to still another embodiment of the present invention.

FIG. 14 is a side view of a portion of an orthopedic implant systemattached to a part of a spinal column.

FIG. 15 is a front view of a portion of an orthopedic implant systemattached to a part of a spinal column.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein, beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

Referring generally to FIGS. 1-2, embodiments of a system 15 fororthopedic implantation are shown. Among the possible implants that canbe a part of system 15 are longitudinal members such as rods 16, 17,bone attachment members such as screws 22, 23, 24, connectors such ascross connectors 25, 26, longitudinal connector 27, lateral connector28, hooks 29, and other devices. It will be understood that other typesof fasteners or connectors (e.g. clamps) can be used in connection withsystem 15 or other aspects of the present disclosure. Further additionalor alternative longitudinal members can also be used, such as the platesor rods disclosed in U.S. Pat. No. 6,485,491, or the rods disclosed inU.S. Pat. No. 5,217,461, both of which are hereby incorporated herein byreference in their entireties.

As will be described further below, the illustrated embodiments ofsystem 15 can be implanted via an open, minimally-invasive or othersurgical approach. Generally, fasteners are inserted into one or morebones, longitudinal members are contoured, if necessary, and surgicallyinserted and connected to the fasteners. The relative angles offasteners with respect to the longitudinal member can be adjusted asnecessary for ease of connection of the longitudinal member to thefasteners. Connectors are fitted to longitudinal members and/orfasteners as necessary or desired, and all elements are locked againstmovement with respect to other parts.

Referring now generally to FIGS. 3-4, there is shown an embodiment ofmulti-axial fastener 22. Fastener 22 includes a receiver member 30, abone anchoring member 31, a base or retaining member 32, a crownassembly 33, and a compression member 34. Receiver member 30 has achannel 35 therethrough adapted to accommodate rod 16 or otherlongitudinal member. An aperture 36, which may be cylindrical, extendsfrom a lower portion 38 of receiver member 30 transversely to and incommunication with channel 35. In a specific embodiment, aperture 36extends from the lower portion 38 to a top portion 40 of receiver member30, and aperture 36 has a threaded portion 42 at or near top portion 40for use when compression member 34 is or includes a set screw or otherelement with external threads. Threaded portion 42 could be outside ofreceiver member 30 if an external compression member is used.Alternatiavely, receiver member 30 could be externally and/or internallyconfigured for compression members using snapping, twisting or othertypes of closures. The lower portion 38 of receiver member 30 has agroove 44. In the illustrated embodiment, groove 44 extends around theentire circumference of aperture 36.

The illustrated embodiment of receiver member 30 of fastener 22 is an“open backed”variety. That is, channel 35 is open through the top ofreceiver member 30, making receiver member 30 generally U-shaped anddefining two branches 18, 19. It will be understood that the principlesof this disclosure apply to “closed backed” fasteners, i.e., those inwhich a longitudinal member receiving channel is not open through thetop of its receiver member, but is essentially a hole through thereceiver member. Examples of such “closed backed” fasteners are shown inU.S. Pat. No. 5,005,562, which is incorporated herein by reference.

A stop surface 45 may be included in receiver member 30 in communicationwith aperture 36. Stop surface 45 is provided to act as a stop for crownassembly 33 (described below). With stop surface 45, crown assembly 33cannot move upward in aperture 36 beyond a certain position. Further,referring generally to FIG. 5, a side opening 46 in the side of aspecific embodiment of receiver member 49 may be provided to allowinsertion of base member 32. Side opening 46 is provided in addition tochannel 35, aperture 36 and groove 44, and may be to the side of andtransverse to aperture 36 and channel 35. It will be appreciated thatside opening 46 could be placed in any part of receiver member 30, suchas directly below channel 35. The compressibility or non-compressibilityof the base or retaining member 32 to be used may determine the minimumwidth of side opening 46, as side opening 46 need not be as wide if thebase member is compressible.

Bone anchoring member 31, in one embodiment, is a screw element having ahead portion 47 and a shank portion 48. Shank portion 48 includes a boneengaging portion 50, which in one particular embodiment has threads,such as for engaging bone tissue, and may also include a non-threadedportion 52. At least part of head portion 47 is preferably, but notnecessarily, spherical, rounded, conical, or otherwise configured forrotation or angulation with respect to receiver member 30 and basemember 32. A top part of head portion 47 includes an opening 54 foraccepting a tool, e.g. a hexagonal opening, for inserting bone anchoringmember 31. It will be understood that an alternative bone anchoringmember in the form of a hook element is also contemplated. Such a hookincludes a head portion identical or similar to head portion 47 of boneanchoring member 31, and a shank portion similar to shank portion 48 ofbone anchoring member 31. The shank portion of such a hook would includeor extend into a curved portion for engaging or connecting to a bone.

Base or retaining member 32, 132, 232 in the embodiments shown in FIGS.3, 4 and 6-9 are similar. Referring generally to base member 32, it issubstantially circular in one embodiment with a flange 56 and a centeropening 58. Center opening 58 is bounded by walls 60, 61. As examples,walls 60, 61 may be a portion of a cone or sphere, or may form a sharpedge. The embodiments of base members 32 and 132 generally form aC-shaped element (FIGS. 3-4, 6-7 and 9), and the embodiment of basemember 232 generally forms the entirety of a circle (FIG. 8). Basemember 32 includes a gap 62 in its circumference along with a centeropening 58. Opening 58 is shown in one embodiment as substantiallycircular, but could also have a conical, spherical, stepped, recessed,and/or other configuration. Opening 58 allows head portion 47 of boneanchoring member 31 to rotate with respect to base member 32, allowingpositioning of bone anchoring member 31 at any of a variety of angleswith respect to longitudinal axis L (FIG. 4) of receiver member 30.

Referring to FIG. 7, it will be noted that the interference of basemember 32 and shank portion 48 of bone anchoring member 31 determines afirst maximum angle α between bone anchoring member 31 and axis L for atleast a portion of the relative positions of bone anchoring member 31and base member 32. Gap 62 acts as a slot or elongation of centeropening 58, so that when bone anchoring member 31 is oriented so thatshank portion 48 is substantially aligned with gap 62, a second, largermaximum angle β between bone anchoring member 31 and axis L is availablebecause interference between shank 48 and base member 32 is eithereliminated or moved outward. In other words, gap 62 provides space inwhich at least a part of shank portion 48 can extend to provide agreater maximum angle β. A wider gap 62, for example a gap 62 that islarger than the diameter of shank portion 48 of bone anchoring member31, allows shank portion 48 to extend through gap 62, and the maximumangle β in that instance is limited only by interference between shankportion 48 and receiver member 30. A narrower gap 62 allows only a partof shank portion 48 into gap 62, and thus the maximum angle β is limitedby the points of interference between shank portion 48 and the edges ofbase member 32 adjacent gap 62. The magnitude of maximum angle β istherefore a function of the width of gap 62.

In the solid-circumference embodiment of base member 232 (FIG. 8),center opening 258 also has a circular portion 258 a and an elongated orslot portion 258 b. When bone anchoring member 31 is used with basemember 232, there is a first maximum angle between bone anchoring member31 and axis L when bone anchoring member 31 is not substantially alignedwith slot portion 258 b. A second larger maximum angle is available whenbone anchoring member 31 is substantially aligned with at least part ofslot portion 258 b. Similar to the discussion above with respect to gap62, it will be seen that the magnitude of that second larger maximumangle is a function of the width and length of slot portion 258 b. Theembodiment of base member 232 in FIG. 8 is shown without one or moreflanges. It will be understood that such flange(s) as flange 52 could beprovided for this embodiment as well. The embodiment of base member 132(FIG. 9) combines features of base members 32 and 232.

Base member 132 is essentially the same as base member 232, with theexception that a gap 162 is provided. Gap 162 can further allow basemember 132 to be radially compressed, e.g. for insertion into groove 44of receiver member 30, or to be radially expanded. In embodiments thatare to be radially compressed or expanded, e.g. base member 32, 132, oneor more notches or indentations 163 (FIG. 9) may be provided around theouter side surface of base member 132. In a particular embodiment, threesuch notches 163 may be provided, one placed substantially diametricallyopposite gap 162, and the remaining two notches 163 placed approximatelyabout 90 degrees from either side of the first notch 163, orapproximately about equidistant between the first notch 163 and gap 162.Such notch(es) 163 provide stress relief for base member 132, reducingor eliminating the risk that base member 132 will not return to itsoriginal shape after radial compression or expansion. It will be notedthat one or more notches similar or identical to notches 163 can beincorporated into other C-shaped embodiments such as base member 32.

Base members 32, 132, 232 may also be configured with one or moreundulating or wavy portions. An example of such an undulating ring isseen in FIG. 17 a of U.S. Pat. No. 6,485,491. Such undulating portionsare preferably sufficiently thin to enable embodiments of base members32, 132, 232 that include them to elastically flatten. These embodimentscan act as a type of spring, exerting a force on the head portion 47 ofbone anchoring member 31. Such force may hold head portion 47 againstcrown assembly 33 (if present), or another part of receiver member 30.Looseness or “slack” in the fastener 22 can thus be reduced orsubstantially eliminated, without preventing all movement of headportion 47. When fastener 22 is locked as described below, the opposingforce on head portion 47 may flatten any undulating portions of a basemember 32, 132, 232 partially or completely.

Crown assembly 33, in the embodiment shown in FIG. 3, includes at leasta crown element 64, which is preferably substantially cylindrical withan internal opening 66 and an undersurface 68. Crown element 64 is sizedto fit within aperture 36 of receiver member 30, so that crown element64 has some freedom of axial movement within aperture 36. Internalopening 66 is provided to allow access to tool opening 54 in boneanchoring member 31 when crown element 64 is above or atop boneanchoring member 31. Undersurface 68 is preferably configured toaccommodate at least a part of head portion 47 of bone anchoring member31. For example, undersurface 68 may be shaped (e.g. spherical, rounded,conical, or otherwise) to allow relative movement between crown element64 and part or all of head portion 47 of bone anchoring member 31. Inthe embodiment in which both undersurface 68 and head portion 47 have arounded or spherical portion, undersurface 68 may have substantially thesame diameter as head portion 47. Further, crown element 64 may includean external groove 70, and crown assembly 33 may also include a C-shapedsnap-ring 72 adapted to fit at least partially within groove 70.Snap-ring 72 assists in base crown element 64 within receiver member 30by interfering with stop surface 45 in receiving member 30.

Snap-ring 72 may also be configured with one or more undulating or wavyportions. Such undulating portions are preferably sufficiently thin toenable embodiments of snap-ring 72 that include them to elasticallyflatten. These embodiments can act as a type of spring between receivermember 30 (e.g. stop surface 45) and crown element 64, exerting a forceon the crown element 64. Such force may hold crown element 64 againsthead portion 47 of bone anchoring member 31 or against a part ofreceiver member 30 (if bone anchoring member 31 is not yet withinreceiver member 31). Looseness or “slack” in the fastener 22 can thus bereduced or substantially eliminated, without preventing all movement ofcrown element 64. When fastener 22 is locked as described below, theforces on crown element 64 may flatten any undulating portions ofsnap-ring 72 partially or completely.

Compression member 34 is shown in one embodiment as an externallythreaded element. Compression member 34 may be a standard set screw or abreak-offset screw such as those disclosed in U.S. Pat. No. 6,478,795,the entirety of which is incorporated herein by reference. Compressionmember 34 may also include reverse angle threads as disclosed in U.S.Pat. No. 6,296,642, the entirety of which is incorporated herein byreference. In the threaded embodiment, compression member 34 isconfigured to thread into threaded portion 42 of receiver member 30 andagainst rod 16, to compress crown element 64 and lock fastener 22 withrespect to rod 16. Alternatively or additionally, compression member 34can include an external element such as a nut or cap, which may havethreads or other features for holding the external element to receivermember 30. If an external element is used, receiver member 30 may beprovided with compatible threads or other features for mating with theexternal element.

Alternative embodiments of a receiver member and a base member aredepicted in FIGS. 10-12. Throughout this disclosure, related featuresare indicated by replacing or adding a new first digit to the numbersidentified above. Referring to FIG. 10, receiver member 330 and basemember 332 can be used with the elements described above in amulti-axial fastener similar to fastener 22, or in other orthopedicimplants. Receiver member 330 is shown with channel 335 and aperture336. It will be appreciated that in one embodiment receiver member 330can include structure similar or identical in form and purpose tothreaded portion 42 and stop surface 45 described above with respect toreceiver member 30.

Receiver member 330 and base member 332 are rotatably connected, andsuch rotatable connection can be achieved in a number of ways. In oneembodiment, receiver member 330 includes a groove 344 or thread (notshown). Groove 344 is shown as external of receiver member 330, but itwill be understood that such a groove 344 or thread could also be placedinside receiver member 330. Base member 332 in this embodiment includesa circumferential flange 352 or threads (not shown) for rotatableconnection to receiver member 330. Base member 332 attaches to receivermember 330 by placing flange 352 into groove 344, preferably in a snap-or press-fit. Where threads are provided on base member 332 and receivermember 330, those threads are engaged to rotatably connect base member332 and receiver member 330. In the embodiment in which groove 344 isinside receiver member 330, flange 352 will extend outwardly from basemember 332, or be otherwise configured to fit with groove 344.

The embodiment of base member 332 depicted in FIG. 10 includes anopening 358 for allowing multi-axial positioning of a bone anchoringmember 31. This embodiment of base member 332 allows loading of crownelement 64 (and snap-ring 72, if used) through lower portion 338 intoaperture 336 of receiver member 330.

Base member 432 can include an opening that permits a larger maximumangle in at least one orientation of the fastener with respect to basemember 432 than in other orientations. As shown in FIG. 11, elongatedportion 458 b can extend through the side of base member 432, creating anotch 455. Base member 432 can be rotated with respect to receivermember 430 so that elongated portion 458 b can be oriented at any of anumber of orientations with respect to channel 435 of receiver member430.

In another embodiment (FIG. 12), opening 558 is non-perpendicular toaxis L of aperture 536 of receiver member 530. In this case, there willbe a first part 574 of opening 558 that is relatively close to receivermember 530 and a diametrically opposed second part 576 of opening 558that is relatively distant from receiver member 530. When fastener 31 isoriented so that shank portion 52 is substantially adjacent to firstpart 574 of opening 558, then the maximum angle of fastener 31 withrespect to axis L is greater than a maximum angle afforded by anotherpart of opening 558.

Alternatively, the rotatable connection of a receiver member and a basemember could be achieved by different structure. For example, receivermember 630 and base member 632 could be rotatably connected via aC-shaped snap-ring 637 (FIG. 13). In this embodiment, receiver member630 includes a groove 644 in a lower portion, and base member 632includes a groove 680 in an upper portion. Snap-ring 637 is sized to fitat least partially within grooves 644 and 680, so that a portion ofsnap-ring 637 extends outside of grooves 644 and 680. To assemble,snap-ring 637 may be placed in one of grooves 644 and 680. Snap-ring 637may be expanded or contracted as necessary to allow it and the part towhich it is connected (receiver member 630 or base member 632) to beconnected to the other part so that snap-ring 637 fits at leastpartially within the other of grooves 644 and 680. When assembled,snap-ring 637 is within at least a part of each groove 644 and 680,thereby holding receiver member 630 and base member 632 together.

Any embodiment of receiver member (e.g. receiver member 630), basemember (e.g. base member 632), and/or snap-ring (e.g. snap-ring 637)could be at least partially formed of a shape-memory alloy, such as thenickel-titanium alloy known as Nitinol®. In the embodiment shown in FIG.13, for example, receiver member 630 and base member 632 may berotatable until implanted, when the change in temperature of the alloycauses a press or interference fit between them, or snap-ring 637 couldexpand or contract with a change in temperature to hold receiver member630 and base member 632 together and/or non-rotatable.

In use, a device such as multi-axial fastener 22 may be implanted asfollows. One or more surgical openings are made proximate to an area ofthe spine or other bones to be instrumented. The surgical openings maybe open, minimally-invasive, or of other types that may be known insurgical practice. The vertebrae or other surgical site is prepared, forexample by abrading tissue, drilling holes, adjusting bony or othertissue, or other steps to prepare and fixate a bone or bones.

Preferably, prior to insertion of fastener 22, receiver member 30, boneanchoring member 31, base member 32 or 232, and crown assembly 33 (ifused) are assembled as described and shown above. In this pre-insertionstate, receiver member 30 is multi-axially positionable with respect tobone anchoring member 31, and base member 32 or 232 is rotatable withrespect to receiver member 30 so that the elongated or slot portion ofopening 58 can point in any direction with respect to receiver member30. Base member 32 or 232 can be intentionally pre-oriented with respectto receiver member 30 by the assembler prior to surgery, or can simplybe placed in groove 44 of receiver member 30 in any orientation. Thesurgeon is able to change the relative orientation of receiver member 30with respect to base member 32 or 232 and/or bone anchoring member 31immediately prior to surgery by rotating bone anchoring member 31 withrespect to receiver member 30 and/or base member 32, or by rotatingreceiver member 30 with respect to base member 32, or both. The surgeonis also able to change those relative orientations during surgery, asfurther described below. Crown assembly 33 (if present) is held withinreceiver member 30 between head 47 of fastening member 31 and stopsurface 45. It will be appreciated that assembly of these parts can takeplace at any time prior to insertion, by the surgeon or other person,and that kits including one or more of each type of part describedabove, in one or more sizes can be provided for the user's convenience.

Once the surgical site is prepared, the assembled implant is insertedinto the site and placed. In the embodiment in which bone anchoringmember 31 is a screw, threaded shank portion 50 may be inserted into aprepared hole in a vertebra. Where bone anchoring member 31 includes aself-drilling screw or a self-tapping screw, a previously-drilled holein the bone, or tapping of the hole with a separate tool, may not benecessary. An appropriate tool may be inserted through aperture 36 ofreceiver member 30 and opening 66 of crown member 64 into tool opening54 of bone anchoring member 31, and then such tool may be used to turnbone anchoring member 31 to insert it in the bone.

When bone anchoring member 31 is inserted into the bone to the desireddepth, the tool is removed, and the surgeon can make adjustments to theorientation of receiver member 30 with respect to bone anchoring member31 or to the orientation of base member 32 with respect to receivermember 30. For example, the surgeon can turn or angle receiver member 30with respect to bone anchoring member 31. The surgeon can also turn basemember 32 in groove 44 with respect to receiver member 30, for instanceby maneuvering receiver member 30 and base member 32 together until apart of bone anchoring member 31 is within an elongated opening in basemember 32 such as gap 62, and then turning receiving member 30 withrespect to bone anchoring member. Bone anchoring member 31 interfereswith base member 32 at gap 62 so that base member 32 cannot turn withreceiver member 30. By turning base member 32 with respect to receivermember 30, the orientation of the elongated part of center opening 58 ofbase member 32 (e.g. gap 62 or slot 158 b) rotates or pivots, so thatthe direction in which bone anchoring member 31 can attain the largestmaximum angulation with respect to receiver member 30 is pivotable andindependent of the orientation of receiver member 30. Other implantdevices, such as additional fasteners 22, multi-axial screws 23, 24,and/or monoaxial hooks 29, can similarly be inserted into the same orother bones.

A longitudinal member, such as spinal rod 16 or 17, can be bent orotherwise contoured and then inserted into the surgical site. Thelongitudinal member is connected to receiver member 30 by insertion of aportion of it into channel 35 of receiver member 30. The longitudinalmember is inserted (or “reduced”) at least to a point so thatcompression member 34 can be connected to receiver member 30 and holdthe longitudinal member within channel 35. Similar longitudinal memberreduction can be done with respect to other screws, hooks, connectors,clamps or other devices. The surgeon can then manipulate the spine andthe implanted devices so that the spine is corrected or placed in atherapeutically improved position.

When the spine and implants are positioned as the surgeon desires, thelongitudinal member is locked within receiver member 30 by tighteningcompression member 34 against the longitudinal member, which pressesagainst crown assembly 33 (if present), fastener member head portion 47,and base member 32. Receiver member 30, particularly channel 35 and itsadjoining surfaces, as well as rod 16 or 17 and/or bone anchoring member31 can be configured so that crown element 64 or crown assembly 33 isnot necessary. Other implant devices are similarly tightened to hold thelongitudinal member, and the spine, in the desired position.

As a part of the process of adjusting the position of the spinal column,one or more spacing devices can be inserted between adjacent vertebrae.Examples of such intervertebral implant devices are disclosed in U.S.Pat. Nos. 5,984,967 and 6,113,637, both of which are incorporated hereinby reference. “Cage”-type intervertebral implants may also be packed orotherwise provided with one or more substances for inducing or promotingbone growth, such as a bone morphogenic protein, as disclosed in U.S.Pat. No. 5,984,967. Referring to FIG. 14, there is shown a possibleembodiment of a fastener 22 connected to a rod 16 as part of a system(such as one of the embodiments of system 15 shown in FIG. 1 or 2), aswell as a intervertebral implant 700 placed in the intervertebral diskspace 702 between two vertebrae 704, 706. Although FIG. 14 shows theimplants placed anteriorly on the spinal column, it is understood thatthey can be placed posteriorly or in any other appropriate or necessaryposition. Referring to FIG. 15, there is shown an implant system 715featuring implants such as those disclosed herein. Bone growth-promotingsubstance 720, such as BMP (bone morphogenic protein), LMP (LIMmineralization protein), bone chips or marrow or other natural tissue,DBM (demineralized bone matrix), or mesenchymal stem cells, along withany necessary or appropriate carriers or other therapeutic composition,is packed in and/or around the implants and vertebrae.

As seen in FIG. 1, a system 15 can include a set of two rods 16, 17attached to separate parts of a bone or spinal column. For example, onerod 16 can be attached to a set of vertebrae on one side, and a secondrod 16 can be attached to another side of the same vertebrae. These rodscan then be connected, for example with cross connector 25. Further,additional smaller rods 17 can be connected via longitudinal connectors27 to rods 16, and can be fixed to vertebrae (e.g. cervical vertebrae)above the level of the vertebrae to which rods 16 are fixed. It will beappreciated that such longitudinal connection of rods can beaccomplished along any contiguous segments of the spinal column, whethercervical, thoracic, lumbar or sacral. It will further be appreciatedthat, in place of such longitudinal connection of larger and smallerrods, a single rod having a portion with a smaller diameter and aportion with a larger diameter can be used. Such a rod is disclosed inU.S. Pat. No. 5,217,461, incorporated herein by reference.

The structures described above are preferably made of biocompatiblematerials such as stainless steel, titanium, nickel-titanium (e.g.Nitinol®) or other shape-memory alloys, certain hard plastics or othersynthetic materials, and the like.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character. It should be understoodthat only the preferred embodiments have been shown and described andthat all changes and modifications that come within the spirit of theinvention are desired to be protected.

1. A bone fixation system, comprising: a receiver member having alongitudinal axis; a bone anchoring member having a head portion and abone-engaging portion, said bone anchoring member having at least afirst maximum angular position and a second maximum angular positionrelative to said axis, wherein said second maximum angular positionincludes a greater angle relative to said axis than said first maximumangular position; and a base member rotatably connected to said receivermember adjacent to said bone anchoring member to permit rotationalmovement of said base member relative to said receiver member about saidlongitudinal axis when said base member is rotatably engaged to saidreceiver member, said base member having at least one wall defining anopening that allows said bone anchoring member to occupy either of saidfirst maximum angular position and said second maximum angular position;and wherein said base member connects to said receiver member so that atleast part of said base member is external of said receiver member, andwherein said at least part of said base member coin rises a lowersurface sortion of said base member that is positioned substantiallyflush with or externally beyond an external bottom surface of saidreceiver member.
 2. The system of claim 1, wherein said base memberopening has at least a first sized portion corresponding to the firstmaximum angular position and a second sized portion corresponding to thesecond maximum angular position.
 3. The system of claim 2, wherein saidfirst sized portion of said base member opening includes a firstopening, and said second sized portion of said base member openingincludes an elongated portion.
 4. The system of claim 2, wherein saidbase member has a side surface, and said second sized portion of saidbase member opening extends to said side surface and forms a notch insaid side surface.
 5. The system of claim 3, wherein said base member issubstantially in the form of a C-shaped compressible member defining agap, and said gap forms at least part of said elongated portion of saidsecond sized portion of said base member opening, said gap providingsaid base member with compressibility to allow said base member to beradially compressed for insertion into a groove in said receiver memberand radially expanded within said groove.
 6. The system of claim 3,wherein said base member is substantially in the form of a continuouscircumference washer member.
 7. The system of claim 1, wherein said basemember connects to said receiver member so that at least part of saidbase member is within said receiver member.
 8. The system of claim 7,wherein said external bottom surface of said receiver member has anaperture, and said base member is insertable into said receiver memberthrough said aperture.
 9. The system of claim 8, wherein said receivermember includes at least one groove communicating with said aperture,and said base member includes at least one flange, and wherein said basemember and said receiver member are rotatably connected by insertingsaid at least one flange into said at least one groove.
 10. The systemof claim 7, wherein said receiver member includes a side surface havingan aperture, and said base member is insertable into said receivermember through said aperture.
 11. The system of claim 10, wherein saidreceiver member includes at least one groove communicating with saidaperture, and said base member includes at least one flange, and whereinsaid base member and said receiver member are rotatably connected byinserting said at least one flange into said at least one groove. 12.The system of claim 1, wherein said receiver member has at least oneexterior portion with a groove, and said base member has at least oneflange, and wherein said base member and said receiver member arerotatably connected by inserting said at least one flange into said atleast one groove.
 13. The system of claim 1, wherein said receivermember has at least one exterior portion with a first groove, and saidbase member has at least one interior portion with a second groove, andfurther comprising a ring member adapted to occupy at least a portion ofsaid first and second grooves.
 14. The system of claim 1, wherein saidreceiver member has at least one exterior portion with a thread, andsaid base member has a threaded portion, and wherein said base memberand said receiver member are rotatably connected by connecting theirrespective threaded portions.
 15. The system of claim 1, wherein saidreceiver member has a channel, and said base member opening is in aplane that is non-perpendicular to said axis so that different parts ofsaid base member opening are different distances from said channel. 16.The system of claim 1 further comprising one or more implants from thegroup consisting of cross connectors, lateral connectors, monoaxial boneanchoring members, multi-axial bone anchoring members, plate members,and occipital fixators.
 17. The system of claim 1, further comprising aspinal rod within said receiver member.
 18. The system of claim 17,wherein said spinal rod has a substantially constant diameter.
 19. Thesystem of claim 17, wherein said spinal rod has a first portion with afirst substantially constant diameter and a second portion with a secondsubstantially constant diameter that is larger than said first diameter.20. The system of claim 1, wherein at least one of said receiver memberand said base member is at least partially made of a shape-memory alloy.21. The system of claim 1, wherein said base member is rotatablerelative to said receiver member about said longitudinal axis to changean orientation of said opening relative to said receiver member, whereina direction of said second maximum angular position relative to saidlongitudinal axis is correspondingly changed independent of anorientation of said receiver member.
 22. The system of claim 21, whereinmovement of said base member relative to said receiver member issubstantially limited to said rotational movement about saidlongitudinal axis.
 23. The system of claim 22, wherein said rotationalmovement about said longitudinal axis is substantially limited by aprojection positioned within a groove extending at least partially aboutsaid longitudinal axis.
 24. The system of claim 23, wherein saidreceiver member defines said groove and said base member defines saidprojection, said groove extending circumferentially about said receivermember.
 25. The system of claim 1, wherein said base member is rotatablerelative to said receiver member about said longitudinal axis; andwherein movement of said base member relative to said receiver member issubstantially limited to said rotational movement of said base memberabout said longitudinal axis.
 26. The system of claim 25, wherein saidrotational movement of said base member about said longitudinal axis islimited by a projection positioned within a groove extending at leastpartially about said longitudinal axis.
 27. The system of claim 1,wherein said receiver member includes a groove extending at leastpartially about said longitudinal axis; wherein said base memberincludes a cylindrical portion and a radial flange portion extendingradially from said cylindrical portion; and wherein said base member isrotatably connected to said receiver member when said radial flangeportion is positioned within said groove to thereby permit saidrotational movement of said base member relative to said receiver memberabout said longitudinal axis.
 28. A bone fixation system, comprising: areceiver member having a longitudinal axis, a groove extending at leastpartially about said longitudinal axis, and at least one wall defining achannel for receiving at least a portion of an elongated body; a boneanchoring member having a head portion and a bone-engaging portion, saidbone anchoring member having at least a first maximum angular positionand a second maximum angular position relative to said receiver member,wherein said second maximum angular position includes a greater anglerelative to said receiver member than said first maximum angularposition; and a base member including a cylindrical portion and a radialflange portion extending radially from said cylindrical portion, whereinsaid base member is rotatably connected to said receiver member whensaid radial flange portion is positioned within said groove to therebypermit rotational movement of said base member relative to said receivermember about said longitudinal axis, said base member having at leastone wall defining an opening that allows said bone anchoring member tooccupy either of said first maximum angular position and said secondmaximum angular position; and wherein said base member connects to saidreceiver member so that at least part of said base member is external ofsaid receiver member, and wherein said at least part of said base membercomprises a lower surface portion of said base member that is positionedsubstantially flush with or externally beyond an external bottom surfaceof said receiver member.
 29. The system of claim 28, wherein said basemember opening has at least a first sized portion corresponding to thefirst maximum angular position and a second sized portion correspondingto the second maximum angular position.
 30. The system of claim 29,wherein said first sized portion of said base member opening includes asubstantially circular portion, and said second sized portion of saidbase member opening includes an elongated portion.
 31. The system ofclaim 30, wherein said base member is substantially in the form of aC-shaped compressible member defining a gap, and said gap forms at leastpart of said elongated portion of said second sized portion of said basemember opening, said gap providing said base member with compressibilityto allow said base member to be radially compressed for insertion ofsaid radial flange portion into said groove in said receiver member andradially expanded within said groove.
 32. The system of claim 30,wherein said base member is substantially in the form of a continuouscircumference washer member.
 33. The system of claim 28, wherein saidbase member connects to said receiver member so that at least part ofsaid base member is within said receiver member.
 34. The system of claim33, wherein said external bottom surface of said receiver member has anaperture, and said base member is insertable into said receiver memberthrough said aperture.
 35. The system of claim 34, wherein said groovecommunicates with said aperture.
 36. The system of claim 28, wherein adirection of said second maximum angular position relative to saidlongitudinal axis is correspondingly changed independent of anorientation of said receiver member.
 37. The system of claim 36, whereinmovement of said base member relative to said receiver member issubstantially limited to said rotational movement about saidlongitudinal axis.
 38. The system of claim 37, wherein said rotationalmovement about said longitudinal axis is substantially limited by saidradial flange portion positioned within said groove extending at leastpartially about said longitudinal axis.
 39. An orthopedic implantapparatus comprising: a receiver member having at least one walldefining a channel for receiving at least a portion of an elongatedbody, said receiver member having a longitudinal axis and a grooveextending at least partially about said longitudinal axis; a boneanchoring member having a head portion and a bone-engaging portion; anda base member including a cylindrical portion and a radial flangeportion extending radially from said cylindrical portion, wherein saidbase member is rotatably connected to said receiver member when saidradial flange portion is positioned within said groove to thereby permitrotational movement of said base member relative to said receiver memberabout said longitudinal axis, said base member permitting multi-axialpositioning of said bone anchoring member with respect to said receivermember, said base member and said bone anchoring member having a firstrelative position wherein the maximum angle between said bone anchoringmember and said axis is a first value, and wherein other relativepositions of said base member and said bone anchoring member allow amaximum angle between said bone anchoring member and said axis that isless than said first value, and said first relative position isindependent of the orientation of said channel of said receiver member;and wherein said base member connects to said receiver member so that atleast part of said base member is external of said receiver member, andwherein said at least part of said base member comprises a lower surfaceportion of said base member that is positioned substantially flush withor externally beyond an external bottom surface of said receiver member.40. A bone fixation system, comprising: a receiver member having alongitudinal axis; a bone anchoring member having a head portion and abone-engaging portion, said bone anchoring member having at least afirst maximum angular position and a second maximum angular positionrelative to said axis, wherein said second maximum angular positionincludes a greater angle relative to said axis than said first maximumangular position; and a base member rotatably connected to said receivermember adjacent to said bone anchoring member to permit rotationalmovement of said base member relative to said receiver member about saidlongitudinal axis when said base member is rotatably engaged to saidreceiver member, said base member having at least one wall defining anopening that allows said bone anchoring member to occupy either of saidfirst maximum angular position and said second maximum angular position,and wherein said base member connects to said receiver member so that atleast part of said base member is external of said receiver member;wherein said receiver member includes a groove extending at leastpartially about said longitudinal axis; wherein said base memberincludes a cylindrical portion and a radial flange portion extendingradially from said cylindrical portion; wherein said base member isrotatably connected to said receiver member when said radial flangeportion is positioned within said groove to thereby permit saidrotational movement of said base member relative to said receiver memberabout said longitudinal axis; wherein said base member is at leastpartially positioned within an aperture in said receiver member; andwherein said at least part of said base member comprises a lower surfaceof said cylindrical portion of said base member that is positionedsubstantially flush with an external bottom surface of said receivermember.
 41. A bone fixation system, comprising: a receiver member havinga longitudinal axis; a bone anchoring member having a head portion and abone-engaging portion said bone anchoring member having at least a firstmaximum angular position and a second maximum angular position relativeto said axis, wherein said second maximum angular position includes agreater angle relative to said axis than said first maximum angularposition; and a base member rotatably connected to said receiver memberadjacent to said bone anchoring member to permit rotational movement ofsaid base member relative to said receiver member about saidlongitudinal axis when said base member is rotatably engaged to saidreceiver member, said base member having at least one wall defining anopening that allows said bone anchoring member to occupy either of saidfirst maximum angular position and said second maximum angular position,and wherein said base member connects to said receiver member so that atleast part of said base member is external of said receiver member;wherein said base member opening has at least a first sized portioncorresponding to the first maximum angular position and a second sizedportion corresponding to the second maximum angular position; whereinsaid first sized portion of said base member opening includes asubstantially circular opening; and wherein said second sized portion ofsaid base member opening includes a first elongated opening portionpositioned on a first side of said substantially circular opening and asecond elongated opening portion positioned on an opposite second sideof said substantially circular opening.
 42. A bone fixation system,comprising: a receiver member having a longitudinal axis, a grooveextending at least partially about said longitudinal axis, and at leastone wall defining a channel for receiving at least a portion of anelongated body; a bone anchoring member having a head portion and abone-engaging portion, said bone anchoring member having at least afirst maximum angular position and a second maximum angular positionrelative to said receiver member, wherein said second maximum angularposition includes a greater angle relative to said receiver member thansaid first maximum angular position; and a base member including acylindrical portion and a radial flange portion extending radially fromsaid cylindrical portion, wherein said base member is rotatablyconnected to said receiver member when said radial flange portion ispositioned within said groove to thereby permit rotational movement ofsaid base member relative to said receiver member about saidlongitudinal axis, said base member having at least one wall defining anopening that allows said bone anchoring member to occupy either of saidfirst maximum angular position and said second maximum angular position;wherein said base member is at least partially positioned within anaperture in said receiver member; and wherein said cylindrical portionof said base member includes a lower surface that is positionedsubstantially flush with an external bottom surface of said receivermember.
 43. A bone fixation system, comprising: a receiver member havinga longitudinal axis, a groove extending at least partially about saidlongitudinal axis, and at least one wall defining a channel forreceiving at least a portion of an elongated body; a bone anchoringmember having a head portion and a bone-engaging portion, said boneanchoring member having at least a first maximum angular position and asecond maximum angular position relative to said receiver member,wherein said second maximum angular position includes a greater anglerelative to said receiver member than said first maximum angularposition; and a base member including a cylindrical portion and a radialflange portion extending radially from said cylindrical portion, whereinsaid base member is rotatably connected to said receiver member whensaid radial flange portion is positioned within said groove to therebypermit rotational movement of said base member relative to said receivermember about said longitudinal axis, said base member having at leastone wall defining an opening that allows said bone anchoring member tooccupy either of said first maximum angular position and said secondmaximum angular position; wherein said base member opening has at leasta first sized portion corresponding to the first maximum angularposition and a second sized portion corresponding to the second maximumangular position; wherein said first sized portion of said base memberopening includes a substantially circular opening; and wherein saidsecond sized portion of said base member opening includes a firstelongated opening portion positioned on a first side of saidsubstantially circular opening and a second elongated opening portionpositioned on an opposite second side of said substantially circularopening.